Until recently, Winchester style magnetic heads have been used exclusively in disc-drive systems having nonremovable discs, obviating the need to load and unload heads from the discs. With the advent of removable discs in systems using Winchester style heads, the need to load and unload these heads has arisen.
Prior to the use of Winchester heads, heads of other designs could be loaded and unloaded onto magnetic discs. In general, the loading onto the magnetic disc was done onto a rotating disc. The combination of the rotating disc and a large air bearing resulting from the use of a head slider having considerable area avoided damage to the disc. However, with the smaller slider areas of Winchester style heads, it is desirable that the loading of the head be onto a stationary disc.
The previously used mechanisms for loading and unloading magnetic heads depend upon solenoid or springdriven motion. Some of these mechanisms attempt to control the velocity of the moving heads by the inclusion of a dashpot damper. In general, however, a solenoid moves the head in one direction while a spring, controlled by the dashpot, moves the head in the other direction. Mechanisms using solenoids and dashpots, however, have a number of disadvantages, one of the primary ones being the high cost of suitable solenoids and dashpots. Also, the velocity of the magnetic heads cannot be controlled with precision by such mechanisms under certain circumstances.
The present invention overcomes all these disadvantages in providing a mechanism that is easy to assemble and therefore relatively inexpensive, as well as reliable.